What Every Boomer Should Know Before Taking Out College Loans

But here's what we hope they realize: They should never borrow more than they can afford to fully pay off by retirement.

"There's no new income in retirement, just savings, so it doesn't make sense to maintain debt that charges a higher interest rate than one is earning on savings," Mark Kantrowitz, publisher of Finaid.org, told Your Money.

"Also (by retirement) total education debt should be less than annual income, and ideally a lot less."

For boomers at the point of no return, there is hope. Those owing federal student loans can qualify for income-based repayment, Kantrowitz says. The monthly payment is determined using a percentage of the borrower's discretionary income, which is based on how much that income exceeds 150% of the poverty line.

"If one's retirement income consists mostly of Social Security benefit payments, that may yield a low monthly loan payment—lower than the 15% of Social Security benefits if a person defaults," Kantrowitz explains.

Such a plan could extend the loan repayments for longer than average—20 to 25 years—but with federal student loans debt is discharged when the borrower dies, so it wouldn't be held against the borrower's estate.